A vehicle typically includes a climate control system which maintains a temperature within a passenger compartment of the vehicle at a comfortable level by providing heating, cooling, and ventilation. Comfort may be maintained in the passenger compartment by an integrated system referred to as a heating, ventilating and air conditioning (HVAC) air-handling system. The HVAC air-handling system conditions air flowing therethrough and distributes the conditioned air throughout the passenger compartment. The design of an HVAC air-handling system includes features that control air flow volume, air temperature, and air flow pathways, for example. Performance of the HVAC air-handling system may comply with particular targets including temperature stratification and air-flow distribution between various outlet vents of the HVAC air-handling system disposed within the passenger compartment.
Many of the HVAC air-handling systems utilize a rotatable fluid distribution door for controlling the flow of air through the air-handling systems. The fluid distribution door is typically rotatable between a plurality of positions associated with a plurality of air flow patterns through the air-handling system, wherein each of the air flow patterns corresponds to a desired flow rate and temperature of the air through the vents of the air-handling system. In many circumstances, the fluid distribution door is rotated to a position wherein edges of the fluid distribution door abut sealing surfaces of a housing in which the fluid distribution door is rotatably disposed to prevent the passage of the air beyond the door. In other circumstances, the fluid distribution door may be rotated to a position allowing for a small flow of air, also referred to as a “bleed,” to pass beyond one of more edges of the door to maintain a miniminum flow of air through at least one of the vents in accordance with the requirements of the passenger of the motor vehicle.
A representative example of a fluid distribution door 100 of the prior art while in the bleed position is illustrated in FIG. 1. The fluid distribution door includes an axis of rotation and at least one door wall 101 extending therefrom. A flexible sealing element 110 is disposed about a perimeter of each of the door walls 101 for engaging surfaces of the housing of the HVAC air-handling system to close off the flow of the air through at least a portion of the HVAC air-handling system. The sealing element 110 generally includes a cross-sectional shape including a base 112 formed at first end adjacent the outer edge of the door surface 101, a bead 114 formed at a distal end of the sealing element 110 forming an outer peripheral surface thereof, and a stem 116 extending between the base 112 and the bead 114. The base 112 forms a connection point for coupling the sealing element 110 to the perimeter of each of the door surfaces 101. The stem 116 generally includes a thickness less than that of the base 112 and the bead 114, respectively. The smaller thickness stem 116 is configured to flex to facilitate forming a suitable seal between the bead 114 of the sealing element 110 and the surface of the housing throughout a plurality of rotational positions of the fluid distribution door 100. The bead 114 is formed to have a larger thickness than the stem 116 to cause air flowing past the bead 114 to experience a small degree of localized turbulence. The localized turbulence is intended to prevent the occurrence of whistling as the air flows past the sealing element 110, especially when the fluid distribution door 100 is positioned in the “bleed” position wherein the bead 114 is disposed immediately adjacent the sealing surface of the housing. However, the exclusive use of the bead 114 formed at the end of the sealing element 110 may not be effective at preventing the incidence of noise, such as whistling, when the flow of the air passes by the door surface 101 under certain circumstances and operating conditions.
One solution to the incidence of unwanted whistling is to further add a secondary noise reducing feature to the portion of the housing forming the sealing surface thereof to further interrupt the flow of the air past the edge of the door surface having the sealing element to produce localized turbulence as described above. Alternatively, another solution includes modifying the outermost edges of the door surface or the sealing element to include various irregularities such as indentations and protrusions to cause a plurality of variable gaps to be present between the fluid distribution door and the sealing surface of the housing even when the fluid distribution is rotated to a position intended to close off the flow of the air past the door surface. The variable gaps similarly promote localized turbulence as the flow of the air passes by the door surface. In either case, such features present at the interface between the fluid distribution door and the housing may introduce an incidence of continuous unwanted air flow past the door surface due to the presence of the variable gaps forming a continuously open flow path. Such secondary features therefore undesirably alter the flow patterns of the air through the HVAC air-handling system when attempting to minimize the incidence of whistling when air flows past each of the door surfaces.
Another solution includes the application of a foam element adjacent the area of engagement of the door surface or sealing element to the sealing surface of the housing for interrupting the flow of the air past the door surface. However, it has been found that the use of such foam elements presents an issue of quality control due to the application of the foam element being inconsistent and operator dependent.
It would therefore be desirable to produce a fluid distribution door that minimizes the incidence of whistling when air is caused to flow past the fluid distribution door while also preventing an unwanted flow of the air past the fluid distribution door when in a closed position intended to block the flow of the air past the fluid distribution door.